1. Field of the Invention
The present invention relates to cooking devices and methods. More particularly, the invention relates to a method, computer program and cooking device for detecting boiling of a liquid.
2. Description of the Prior Art
Food preparers often desire to detect when liquids such as water or water combined with food items first begin to boil and to then maintain a controlled or “soft boil” for the duration of a cooking period. Such steps are often done manually. For example, a food preparer typically places a pot or other cooking vessel filled with water on a heating element, heats the pot at high power, visually observes the water for signs of boiling, and then manually adjusts the power or heating level of the heating element to maintain a soft boil thereafter. Although such manual boil detection methods are generally effective, they require a great deal of manual supervision and control and are, therefore, inefficient for establishments which prepare large amounts of food, such as restaurants or food processors. Such manual methods also often result in overheating and resultant boiling over of the liquids.
Food thermometers and other temperatures sensors can, of course, be used to monitor the temperature of liquids and detect boiling, but such sensors still require manual supervision and monitoring. Moreover, sensors must be placed in contact with the liquids and therefore must be frequently cleaned. The sensors also often fall into the cooking vessels or are dropped, misplaced, etc.
Systems and methods for automatically monitoring and controlling the temperature of liquids in a cooking vessel have been developed to alleviate some of the above-described problems. For example, U.S. Pat. Nos. 5,951,900; 4,587,406; and 3,742,187 disclose non-contact temperature regulation devices and methods using radio frequency transmissions to communicate temperature information between a cooking vessel and an induction heating appliance.
However, the systems described in these patents have never been developed and are limited in many respects. Ranges and cooking vessels have been developed that use temperature feedback based on temperature information gathered from the vessel to vary power output to the vessel and thereby control its temperature. One such system employs an infrared sensor that is an integral part of a cooking hob. The infrared sensor is mounted on a cylindrical casing designed to direct an infrared sensing beam onto a specific portion of the cooking vessel. The temperature information gathered from the infrared sensor beam is used to alter the power output of the hob. Unfortunately, such a system suffers from a number of limitations, including, for example, an undesirably extreme sensitivity to changes in the emissivity of the region of the vessel on which the infrared sensor beam is directed. If the vessel's surface becomes soiled or coated with oil or grease, the emissivity changes and, as a result, the perceived or sensed temperature is not the actual temperature.
Another such cooking system uses a sensing unit which rests upon the handle of the cooking vessel and directs an infrared sensor beam downward onto the food within the vessel to sense the temperature of the food. The temperature information is then converted into a radio frequency signal that is transmitted to a radio frequency receiving unit within an induction range. This radio frequency temperature information is used to alter the power output of the range to control the temperature of the vessel. Unfortunately, this system also suffers from a number of limitations, including, for example, an excessive sensitivity to the emissivity of the food surfaces within the pan.
Moreover, none of these prior art systems and methods accurately detect boiling of liquids and provide an alert or other indication of the boiling. Accordingly, there is a need for an improved method or system for accurately and quickly detecting when liquids within a cooking vessel begin to boil.